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Патент USA US3087487

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April 30, 1963
E. A. THOMPSON
3,087,479
MECHANICAL LASH ADJUSTER
Filed NOV. 13, 1961
I|
2 Sheets-Sheet 1
‘
N0o
/ 24
INVENTOR.
EARL A. THOMPSON
ATTORNEY
April 30, 1963
E. A. THOMPSON '
3,087,479
MECHANICAL LASH ADJUSTER
_ Filed NOV. 15, 1961
2 Sheets-Sheet 2
/45
/46
/32
E15
/36
854m A. THOMPSd/V
ATTORNEY
United States Patent ()??ce
1
3,087,479
Patented Apr. 30, .1963
2
in the direction of increased lash by means of a ?xed
3,087,479
abutment positioned on the engine itself, such potential
lash being removed after the valve seats by a. biasing
spring connected to pivot the eccentric back in the direc
MECHANICAL LASH ADJUSTER
Earl‘A. Thompson,_13,00 Hilton Road, Ferndale, Mich.
Filed Nov. 13, 1961, Ser. No. 151,930
5 Claims, (Cl. 123-90)
tion of decreased lash.
Further objects and advantages of the present invention
will be apparent from the following description, reference.
being had to the accompanying drawings wherein several
This invention relates to lash adjusting mechanism‘ such
as is adapted for use with engine valve operating trains,
and more particularly to an extremely simpli?ed system
for compulsively creating potential lash while the train 10
formslof the present invention are illustrated.
FIGURE 1 is a purely diagrammatic illustration of the
is loaded so that a lash take-up'device may preclude actual
lash as the load on the train is relieved;
operational theory of the present invention.
FIGURE 2 is~a developed diagram of valve stem travel
as compared‘with cam con?guration.
The modern high compression overhead valve type of
automotive engine customarily utilizes valve trains'of' the
FIGURE 3 is a cross-sectional elevational. view of a
rocker arm type-which valve’ trains, being fairly long, are' 15 rocker arm pivoted about an upright stud and including
the lash adjusting arrangement of this invention.
frequently provided with automatic lash adjusting devices.‘
FIGURE 4 is a fragmentary top view of the valve.
Such devices, asheretofore utilized commercially, are al
actuating end of suchrocker arm.
most entirely of the hydraulic type; however, the senstiivity
of hydraulic valve lifters to varnish and dirt has’led de
FIGURE 5 is a cross-sectional elevational view of a
signers to seek improved reliability in‘ automatic lash ad 20 rocker arm pivoted about a longitudinal shaft and includ
justers through the use of purely mechanical devices.
ing the lash adjusting. arrangement of this invention.
FIGURE 6. is a fragmentary top view of the valve
Heretofore, mechanical lashv adjusters, loaded by a lash’
take-up spring, have repeatedly been proposed which‘ de
actuating end of such a rocker arm.
The invention has been illustrated in embodiments suit
tional requirement between contacting surfaces‘to create 25 able for use with valve trains which employ fulcrumed‘
pend for their operational success upon a critical fric
potential lash whenever the valve is actuated. Frequently
this is exempli?ed by use of a force-multiplying mecha
rocker arms Regarding FIGURE 1, such valve trains
ordinarily comprise a valve 10 having a stem 12 and‘ a
?ared head ‘14 which is biased against an annular seat 16
nism, such as a wedge, eccentric or a‘ helix utilized at or
in the engine 18;by means of. a heavy valve seating spring
operate under ideal conditions, unavoidable small changes" 30 20. The valve is mounted for limited longitudinal recip
near the critical friction angle. While such devices may
in the friction co-e?icient which arise under actual op
rocatorymotion by means of a tubular valve guide 22
erating conditions render such sensitive devices inherently
unreliable. Likewise, proposals for self-locking force
positioned in the engine 18' whereby force applied'to the
end of the valve stem 12. compresses the spring 20'andl
shifts the head 14 of the valve away from the ?xed seat
multiplying type lash adjusters with angles safely below
the critical friction angle have depended upon'critical fric 35 16. Such a valve is operated by means of a cam 24.‘
rotated by a camshaft 26 journalled in the engine 18.
tional requirements elsewhere, either'in the driving'or the
Motion is transmitted from the cam surface to the
reaction connection, or both, with the means for operating
valve stem by means of a valve actuating, train which
the force-multiplying arrangement. Again, such connec
ordinarily may comprise a cam follower or tappet 28,
tions may hold and release at the proper times under
speci?c conditions, but are similarly subject to diverse en 40 a push rod arrangement 30‘, and a rocker arm assembly
vironmental factors during engine operation that render
them not entirely satisfactory.
.It has recently been‘ proposed to shift an inherently
32.
motive engines, the expense of providing the various‘com
ponent parts which‘ comprise the clutch driver and clutch
releaser tend to' make the initial and repair costs prohibi
ing train varies in effective length. When the trainis
too long, for instance, the valve will be held off its seat
The rocker arm may be 'fulcrumed at 34 inter.
mediate its ends to a pivot ?xed on the engine 18, and
may have means 36 at one end thereof forming a push
self-locking force-multiplying lash adjusting'device rela
rod abutment and means 38 at the other end thereof’
tive to the valve train by means of fully compulsive driv~ 45 forming a valve stem abutment. As the rotating cam
ing and reaction connections not dependent upon critical
, 24 presents a rising face to the tappet 28, it will be clear
friction angles. This is accomplished by providing a
that upward motion of the push rod arrangement 30 will
positive grip clutch which cocks itself during the valve‘
oscillate the rocker arm 32 clockwise (FIGURE 1) about
opening stroke and then positively grips the force-multiply
the ?xed pivot 34 to open the valve 10; as the cam.
ing mechanism during the valve closing stroke to move 50 24 presents a falling face tothe tappet 28, the valve clos
the mechanism to introduce potential lash into the train,
ing spring 20 maintains a counter-bias on the entire valve
a separate releasing device becoming operative before
actuating train forcing such linkage members back in re
the valve seats to disengage the clutch'so that the'lash take
sponse to the falling cam contour.
up spring may function upon valve seating. While such
It has long been appreciated that because of tempera
devicesare certainly operative during actual use in auto 55 ture‘ requirements and wear conditions, the valve actuat
even when the cam presents its base circle to the follower,
tive for mass production use.
a very undesirable condition resulting in’ burned valves.
Accordingly, it is an object of the present invention to 60 When the train is too short, on the other hand, such lash
provide a spring-loaded mechanical lash adjuster utilizing
in the system creates noisy operating conditions. This
an inherently self-locking force-multiplying mechanism
invention provides means for controlling the effective
which is shifted in the direction of increased lash by
length of the valve actuating train by. introducing poten
‘positive means including fully compulsive driving and
tial lash into the train each cycle so that the valve may
reaction connections and which is extremely simple’ and 65 seat properly, and then’ eliminating all actual lash from.
desirably inexpensive to manufacture, adjust and main
the train prior to the next valve opening so that unde
tain.
More particularly, it is an object of the present inven
tionto provide a. mechanical lash adjuster comprising an.
eccentric pivoted in one end. of a rocker arm to form a
portion of the valve actuating train, which eccentric is
positively driven about its pivot on the valve opening stroke
sirable noise will be eliminated.
Such a result may be accomplished by the elements
70
illustrated purely schematically in FIGURE 1. There,
the push rod arrangement 30 is shown composed. of sev
eral segments, the two lowermost of which are guided
for rectilinear motion in bushings 40‘ which form fully
3,087,479
3
4
compulsive reaction connections for lateral forces. These
two_ push rod segments are interconnected by a wedge
device 42 which may be shifted laterally relative to the
stem comes to rest with the valve head on its seat earlier’
valve train to vary the effective length thereof.
The
slope of the wedge surface is well below the critical fric
tion angle, whereby such device may be termed self-lock
ing; that is, the force of valve train load created by the
valve seating spring 20 is unable to squeeze the wedge
laterally to the left in the direction of increased lash.
than the cam has allowed the operating members of the‘
train to reach the end of their return travel. The lash
take-up spring 44, however, now takes over control of
the member 42 since that member is now entirely free.
of the one-way abutment drive and the locking force of
the valve spring. As the cam recedes further, the mem-'
ber 42 is driven to the right by spring 44 to thus lengthen1
the train as fast as the contour of the cam will permit.‘
The force-multiplying wedge is biased relative to the 10 The increment of potential lash which was introduced
valve train in the direction of decreased lash by means
of a lash take-up spring 44. This spring is not strong
by the one-way drive becomes wiped out and the parts
come to rest with no lash in the system.
enough to shift the wedge relative to the train while the
In FIGURES 3 through 6, two operative embodiments
train 18 under valve spring load; consequently, its acts
only after the valve has seated and the cam approaches
of the lash adjusting system of this invention are illus
trated. In FIGURES 3 and 4, an embodiment is dis
closed for use with an upright rocker arm pivot support
ing stud. In FIGURES 5 and 6, an embodiment is shown
its. base circle whereupon such lash take-up spring may
shift the wedge to remove slack from the train prior to
the next valve opening stroke.
for use with a longitudinal rocker arm pivot shaft.
In
FIGURES 3 and 4, a rocker arm 132 of the trough
This invention provides positive means for shifting the
force-multiplying wedge 42 in the direction of increased 20 shaped or dished variety is individually pivoted about a
semi-spherical fulcrum 134 ?xed on the engine and in
lash each time the valve is actuated to insure proper
seating thereof.
Such positive means may include a
fully compulsive one-way drive which will completely
disengage with the force-multiplying mechanism by the
cludes means forming a push rod abutment 136 at one
end thereof to receive a push rod 130 and a valve stem
abutment 138 at the other end thereof. Semi-permanent
time the valve seats so that the lash take-up spring may 25 adjustments in the length of the valve actuating mech
anism may be obtained by means of an adjusting nut 140
operate. Such a drive may include a single pair of abut
of the self-locking variety which effects an upward or
ments shiftable relative to one another in response to
downward positioning of the fulcrum 134.
motion of the valve train itself. Such a pair of abut
The valve stem actuating end of the rocker arm 132
ments will come together from spaced positions to an
includes lash adjusting mechanism according to this in
engaged position of driving contact; the engaged posi
vention. An eccentric roller 142 may be trunnioned on
tion may include driving contact of either the direct va
a shaft 143 for oscillatory motion in the bifurcated end
riety involving no further relative shifting, or the cam
of the rocker arm. A lash take-up spring 144 connected
ming or “Wiping” variety involving relative shifting while
to the eccentric at 145 may bias the high side of the ec
engaged which may be smoothed by the addition of a
roller or other wear inhibiting device. For instance, a 35 centric towards the valve stem to wipe out potential lash
after the valve seats. An abutment cam surface 146 on
roller abutment 46 associated with the self-locking force
the eccentric may be designed to engage a ?xed abutment
multiplying mechanism 42 is positioned to approach and
comprising a rollable sleeve 147 on a shaft 148 suitably
engage a camming abutment 48 ?xed on the engine 18.
On the valve opening stroke, as the push rod arrange 40 mounted on the engine during the valve opening stroke
to oscillate the eccentric about its trunnion 143 in the
ment is being lifted by the rising face of the cam 24,
direction of increased lash. The distance between the
the abutments 46 and 48 will come together forming a
center of the eccentric and the center of its trunnion
fully compulsive driving connection and shift the wedge
mounting in the rocker arm is large enough to provide
42 to the left in the direction of increased lash to create
the desired distance differential to introduce the required
potential lash in the train. During the entire valve clos
ing motion, it will be obvious that the two abutments 45 amount of potential lash, yet is small enough to provide
a moment arm arrangement which is so short so as to be
46 and 48 move steadily apart because the wedge is
held in its shifted position by the locking angle thereof.
completely self-locking against the valve Spring load on
the actuating train.
After the valve seats, the lash take-up spring 44 may then
In FIGURES 5 and 6, a rocker arm 232 is mounted for
become operative to bias the wedge to the right in the
50 oscillation about a pivot shaft 234 ?xed on the engine
direction of decreased lash through the distance required
and includes means forming a push rod abutment 236 at
to take up any actual lash that may have existed in the
train. Thus, as the cam begins to lift the push rod ar
one end thereof to receive a push rod 231} and a valve
stem abutment 238 on the other end thereof. Semi-per
rangement on the next valve opening stroke, all lash
manent adjustment in the effective length of the valve
will be removed from the train and silent operation will 55 actuating mechanism may be obtained by means of an
be insured.
adjusting screw 240 threaded in the rocker arm and as
In FIGURE 2, there is shown by the line 50‘ a hori
sociated with the push rod abutment 236 thereof. A
zontal plot of cam motion, but showing only the por~
self-locking eccentric roller 242 may be trunnioned on a
tion of the action when the lobe of the cam is effective.
shaft 243 for oscillatory motion in the bifurcated valve
The upper line 52 plots the corresponding movement of 60 stem actuating end of the rocker arm. A shoulder 245
the valve stem to show the differences which are intro
of the eccentric is biased in the direction of decreased
duced by the lash adjuster mechanism. It will be seen
lash by means of a lash take-up spring 244. An abut
from FIGURE 2 that the cam motion and the valve stem
ment cam surface 246 on the eccentric may be designed
to engage a ?xed abutment comprising a rollable sleeve
the rising part of the cam ramp due to the non-slipping 65 247 on a ?xed shaft 248 mounted on the engine during
quality of the wedge. After point 54, the one-way drive
the valve opening stroke to turn the low side of the ec
motion correspond exactly during the initial portion of
begins to shift the force-multiplying member 42 in the
centric towards the valve stem to positively introduce po
direction of increased lash. This motion introduces an
tential lash into the train.
increment of potential lash into the valve train. At a
In operation, both the FIGURE 3 and the FIGURE 5
time after maximum cam rise is completed at point 56, 70 embodiment function similarly and upon the theory illus
the two abutments 46 and 48 will no longer retain 0P
trated in FIGURES l and 2. As the rocker arm is oscil
erative engagement with one another and thereafter no
lated in a clockwise direction about its engine mounted
fulcrum by action of cam and push rod on the valve open
further lash is introduced into the train, and the valve
ing stroke, the abutment cam surface on the eccentric
stem follows the motion of the cam until a point such
as 58 is reached where the valve seats. Thus, the Valve 75 will approach and engage the abutment roller ?xed on
,
73,087,479
.
6
the engine and oscillate the eccentric in-a counter-clock~
means in the one direction from a mid-stroke posi
wise direction relative to the rocker armto a given point
tion through'the distance requiredto reach thelimit
to introduce potential. lash into the valve operating
of itsastroke to create a corresponding amount of po
train. On the valve closing stroke, as. the-rocker‘ arm
oscillates back in a counter-clockwiseLdirection about its 5
tential Ilash in the train,
the force-multiplying means being inherently self-lock
fulcrum, such potential lash Will'be retainediiin the ‘valve
actuating train by the self-locking design of theeccen-tric
ing against the force of valve train load to retain such
amount of potential‘ lash in the train during valve
to insure proper seating of the. valve. As the valve seats
and ‘before the rocker arm has completed'its- ?nal incre
closing motion of the train as the abutments disen
gage and‘move away from one another,
ment. of return motion‘ following the falling contour 10
of the'cam, the. lash take-up spring which is too weak
to operate while the trainisloadedbecomes effective
and a lash take-up spring having suf?cient- force to
rotate the force-multiplying means while the train is
loaded and connected ‘to rotate the force-multiplying
to oscillate the‘ eccentric in a clockwise direction relative
to the rocker arm about its trunnion to‘ wipe out any
means in the return direction away from its‘ stroke
potential lashthat had? been introduced» into: the train.
Thus, allslash is removedrfrom-the valve actuating train
and, on the next valve stroke, the eccentric will-act as
an integral part of the linkage until the ‘abutment cam
required to remove actual lash from-the trainee-the
load on the train is relieved by seating of-the valve.
3: A lashadjusting system of the mechanical type for a
valve-operating train of-an engine > comprising in combina
surface thereon comes into contact with the ?xed» abut
tion therewith
limitv to a’ mid-stroke position through the distance
ment to again introduce an increment of potential lash 20
into thetrainr
While the embodiments of the invention herein dis
an» eccentric rotatable in one direction and return
through a limited stroke- to decrease and increase,
respectively, the effective length of the train by a pre
determined amount,
a- single pair of one-way drive abutments movable to
closed constitute preferred forms, it ,isto be understood
that other forms might be adapted, allcorning within-the
scope of the claims which follow.
I claim:
ward ‘and away from one another between spaced and
engaged relationships in response'to valve opening
and valve closing motion of the train, respectively,
1. A lash adjusting system ofjthe .mechanicaltype for
a valve operating train of an engine‘ comprising inicombi
nation therewith‘
one of the abutments being associated with the eccen
tric and the other abutment-being located to engage
'
force-multiplyingmeans-shiftable in- one direction‘ and
return through a limitedstroke todecrease and in
crease, respectively, the effective length of the train
30'
by a predetermined. amount,
a single pair of abutments movable toward and away
from one another between spaced and engaged rela 35
tionships in response to valve opening and valve
closing motion of the train, respectively, one of the
abutments being associated with the force-multiply
ing means and the other abutment being located to
engage the one abutment part way through the valve 40
'
the one abutment part way’ through the valve opening
motion ofthe train and thereafter compusively rotate
the eccentric in the one direction from a mid-stroke
position through the distance required to- reach the
limit of its stroke to create a corresponding amount
of potential lash in the train,
the eccentric being inherently self-locking against the
force of valve train load to retain such amount of
potential lash in the train during valve closing mo
tion of the train as the abutments disengage and
move away from one another,
-
opening motion of the train and thereafter compul
and a lash take-up spring having insu?icient force to
sively drive the force-multiplying means in the one
direction from a mid-stroke position through the
rotate the eccentric while the train is loaded and con
nected to rotate the eccentric in the return direction
‘away from its stroke limit to a mid-stroke position
through the distance required to remove actual lash
from the train as the load on the train is relieved by
distance required to reach. the limit of its stroke to
create a corresponding amount of potential lash in 45
the train,
the force-multiplying means being inherently self-lock
ing against the force of valve train load to retain
such amount of potential lash in the train during
seating of the valve.
4. A lash adjusting system of the mechanical type for a
valve operating train of an engine comprising in combina
valve closing motion of the train as the abutments 50 tion therewith
disengage and move away from one another,
and yieldable biasing means having insu?icient force
to shift the force-multiplying means while the train
is loaded and connected to shift the force-multiply
ing means in the return direction away from its 55
stroke limit to a mid-stroke position through the
a rocker arm
means intermediate the ends of the rocker arm forming
a fulcrum,
means on one end of the rocker arm forming a push rod
connection,
means on the other end of the rocker arm forming a
distance required to remove actual lash from the
train as the load on the train is relieved by seating
of the valve.
valve stem- connection,
one of the means including rotary wedge type force
2. A lash adjusting system of the mechanical type for a 60
valve operating train of an engine comprising in combina
tion therewith
rotary wedge type force-multiplying means rotatable in
turn through a limited stroke to decrease and increase,
respectively, the effective length of the train by a pre
determined amount,
a single pair of one-way drive abutments movable to
Ward and away from one another between spaced
and engaged relationships in response to valve open
one direction and return through a limited stroke to
decrease and increase, respectively, the effective 65
length of the train by a predetermined amount,
a single pair of one-way drive abutments movable to
ward and away from one another between spaced
and engaged relationships in response to valve open
ing and valve closing motion of the train, respec 70
tively, one of the abutments being associated with the
multiplying means rotatable in one direction and re
ing and valve closing motion of the train, respec
tively, one of the abutments being associated with
the force-multiplying means and the other abutment
being located to engage the one abutment part way
through the valve opening motion of the train and
thereafter compulsively rotate the force-multiplying
force-multiplying mean-s and the other abutment be
ing located to engage the one abutment part way
means in the one direction from a mid-stroke posi
through the valve opening motion of the train and
thereafter eompulsively rotate the force-multiplying 75
of its stroke to create a corresponding amount of po
tion through the distance required to reach the limit
tential lash in the train,
3,087,479
7
8
the force-multiplying means being inherently self-lock
on the engine to engage the one abutment part way
ing against the force of valve train load to retain
such amount of potential lash in the train during
valve closing motion of the train as the abutments
through the valve opening motion of the train and
thereafter compulsively rotate the eccentric in the
one direction from a mid~stroke position through the
distance required to reach the limit of its stroke to
create a corresponding amount of potential lash in
disengage and move away from one another,
and a lash take-up spring having insu?‘icient force to
rotate the force-multiplying means while the train is
loaded ‘and connected to rotate the force-multiplying
means in the return direction away from its stroke
limit to a mid-stroke position through the distance 10
required to remove actual lash from the train as the
force of valve train load to retain such amount of
potential lash in the train during valve closing mo
tion of the train as the abutments disengage and
load on the train is relieved by seating of the valve.
5. A lash ‘adjusting system of the mechanical type for
a valve operating train of an engine comprising in com
bination therewith
the train,
the eccentric being inherently self-locking against the‘
move away from one another,
15
‘a rocker arm,
means intermediate the ends of the rocker arm forming
a fulcrum and means on one end of the rocker arm
forming a push rod connection,
and a lash take-up spring having insu?icient force to
rotate the eccentric while the train is loaded and con
nected to rotate the eccentric in the return direction
away from its stroke limit to a mid-stroke position
‘through the distance required to remove actual lash
from the train as the load on the train is relieved by
seating of the valve.
means on the other end of the rocker arm forming a 20
valve stem connection including a trunnion mount
mg,
an eccentric trunnioned thereon with its surface engage
References Cited in the ?le of this patent
UNITED STATES PATENTS
‘able with the end of a valve stem and being rotatable
1,707,749
Almen ________________ __ Apr. 2, 1929
in one direction and return through a limited stroke 25
1,948,063
Burkhardt ____________ __ Feb. 20, 1934
to decrease and increase, respectively, the e?ective
length of the train by a predetermined amount,
a ‘single pair of one-way drive abutments movable to~
ward and away from one another between spaced
and engaged relationships in response to valve open 30
ing and valve closing motion of the train, respec
tively, one of the abutments being associated with
the eccentric and the other abutment being located
1,950,590
Berry _______________ __ Mar. 13, 1934
1,979,348
2,200,152
2,706,974
2,827,028
Russell _______________ __ Nov. 6,
Burkhardt _____________ __ May 7,
Vermaire ____________ __ Apr. 26,
Dadd _______________ __ Mar. 18,
1934
1940
1955
1958
FOREIGN PATENTS
829,737
Great Britain __________ __ Mar. 9, 1960
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